1. Field of the Invention
The present invention relates to a multidirectional input device, and more particularly, to a multidirectional input device in which a plurality of electric parts can be simultaneously operated by manipulating a control shaft.
2. Description of the Related Art
The present inventors disclose a multidirectional input device in U.S. patent application Ser. Nos. 09/332753 and 09/333276. In the disclosed conventional multidirectional input device (as shown in FIGS. 14 to 20), a first interlock member 32 having a slot 32a is turnably mounted in a cavity of a box-shaped frame 31. The first interlock member 32 is turned to change the resistance of a variable resistor 33 mounted on the frame 31.
A control shaft 34 has a shaft support portion 34b formed at the center and a pair of shaft portions 34a disposed in a direction orthogonal to the axis of the shaft support portion 34b. The control shaft 34 is passed through the slot 32a of the first interlock member 32 so as to be movable along the slot 32a.
The shaft portions 34a are turnably supported by a second interlock member 35, thereby allowing the control shaft 34 to be tilted in the A--A direction.
The second interlock member 35 is made of synthetic resin, and is placed below the first interlock member 32 and is orthogonal thereto.
The second interlock member 35 comprises a rectangular side wall 35b having a center opening 35a for passing the control shaft 34 therethrough, a pair of circular holes 35c formed in the opposing sides of the side wall 35b so as to be engaged with the shaft portions 34a of the control shaft 34, and part operating portions 35d and 35e protruding outward from the side wall 35b.
The shaft portions 34a of the control shaft 34 are snap-fitted in the circular holes 35c, and the control shaft 34 is thereby held by the second interlock member 35.
The second interlock member 35 is turnably supported by the frame 31 to allow the control shaft 34 to be tilted in the B--B direction. A variable resistor 36 mounted on the frame 31 is controlled by the part operating portion 35d, and a pushbutton switch 37 mounted on the frame 31 is operated by the part operating portion 35e.
At the shaft support portion 34b in the lower part of the control shaft 34 placed in the frame 31, an operating member 38 is disposed to move in the axial direction of the control shaft 34.
The operating member 38 is made of resin, and has a base portion 38a having a lower surface curved like a saucer. A cylindrical boss portion 38b projects upward from the center of the base portion 38a, and a shaft hole 38c penetrates through the center of the boss portion 38b.
The shaft support portion 34b of the control shaft 34 is fitted in the boss portion 38b of the operating member 38 so that the operating member 38 can move in the axial direction of the shaft support portion 34b.
An urging member 39 formed of a coil spring is interposed between the control shaft 34 and the operating member 38.
A bottom plate 40 is placed under the operating member 38 so as to close the bottom of the frame 31. The bottom of the operating member 38 is elastically contacted with the flat inner bottom face of the bottom plate 40 by the urging member 39.
The operation of the conventional multidirectional input device will now be described. When operating force is not applied to the control shaft 34 (i.e., when no load is imposed), the operating member 38 is elastically contacted with the inner bottom face of the bottom plate 40 by the elastic force of the urging member 39, the saucerlike bottom face of the base portion 38a is in the horizontal position, and the control shaft 34 is in the neutral upright position (as shown in FIGS. 15 and 17).
When the control shaft 34 is tilted along the slot 32a of the first interlock member 32 in the direction B--B (see FIGS. 15 and 17), the second interlock member 35 turns on the mounting positions on the frame 31, and the operating member 38 is brought into the states shown in FIGS. 19 and 20 and is tilted while the bottom face of the base portion 38a moves in sliding contact with the inner bottom face of the bottom plate 40. This causes the boss portion 38b of the operating member 38 is pushed into the control shaft 34 against the elastic force of the urging member 39.
In the neutral state shown in FIG. 17, clearances K1 and K2 serve as play on the right and left sides of the control shaft 34 between the control shaft 34 and the second interlock member 35 because of the connecting structure therebetween.
As shown in FIG. 18, when the control shaft 34 is initially tilted, the clearance K1 on the tilting side is lost, and the clearance K2 on the opposite side increases.
When the tilting operation is continued in this state, the operating member 31 is brought into a state shown in FIG. 19, and then, into a state shown in FIG. 20 in which it is tilted at a predetermined angle.
When the operating member 38 is tilted by a greater angle than a certain angle, the force in the surface direction of the bottom plate 40 by the spring force of the urging member 39 exceeds the friction force between the operating member 38 and the bottom plate 40 between the states shown in FIGS. 19 and 20. The operating member 38 consequently slides in the direction of the arrow D, and the clearance shifts from the clearance K2 to the clearance K1. This shift operation is transmitted as a tactile feel to the control shaft 34, which impairs operability.
When the second interlock member 35 is turned, the resistance of the variable resistor 36 is changed by the part operating portion 35d. When the operating force applied to the control shaft 34 is removed after the operation of the variable resistor 36 is completed, the operating member 38 automatically returns to the horizontal position because of the elastic force of the urging member 39, and the control shaft 34 also automatically returns to the neutral position.
When the control shaft 34 is tilted along the center opening 35a of the second interlock member 35 in the direction A--A in FIG. 16, the first interlock member 32 is turned to adjust the variable resistor 33.
Description will now be given of the operation of the pushbutton switch 37 serving as an electric part in addition to the variable resistors 33 and 36. First, the control shaft 34 is pressed down in the direction of the arrow C, as shown in FIG. 16.
Then, the second interlock member 35 is moved down because of pressure, and the part operating portion 35e presses a stem portion of the pushbutton switch 37 to turn the pushbutton switch 37 on and off.
When the control shaft 34 is released from pressing, it is returned to the initial state by the urging member 38.
The control shaft 34 may be pressed in the direction of the arrow C not only in the neutral position, but also when it is tilted to control the resistances of the variable resistors 33 and 36.
When the control shaft 34 is tilted in the conventional multidirectional input device, the bottom of the operating member 38 moves in sliding contact with the inner bottom face of the bottom plate 40. Therefore, when the operating member 38 is tilted at a greater angle than a certain angle, it slips in the direction of the arrow D, and this slip is transmitted as a tactile feel to the control shaft 34, which impairs operability.